This invention relates to a paper feeder provided independently from an image forming apparatus for feeding copy paper to the image forming apparatus, and also an image forming apparatus provided with the same.
There have been conventionally known a paper feeder for feeding copy paper to an image forming apparatus as an optional device of a copying machine, a printer, or the like image forming apparatus.
This paper feeder has two types of cutting modes in which a roll of copy paper (roll paper) is cut to be fed to the image forming apparatus: a normal cutting mode and a synchronous cutting mode. In the normal cutting mode, the roll paper is cut to a size set in an operation unit. On the other hand, in the synchronous mode, when a trailing end of a document to be fed to an exposure unit is detected by a document sensor provided in a rear portion of a document setting portion of the image forming apparatus, whereby the sensor detects a size of the document, the roll paper is automatically cut in correspondence with the document size. More specifically in the case where the synchronous cutting mode is selected, a leading end of the roll paper is transported from the paper feeder to a specified position in the image forming apparatus. After the feed of the document and that of the roll paper are started in synchronism with each other, the roll paper is automatically cut upon the document sensor detecting the trailing end of the document.
In order to prevent an image of a document from being copied obliquely, some of image forming apparatuses of the above type are provided with correcting mechanism for automatically setting the document in position in the case where the document is set obliquely with respect to a feeding direction thereof. However, this mechanism has resulted in a complicated construction and a higher cost.
On the contrary, in an image forming apparatus provided with no such correcting mechanism, when a document is set obliquely in a document setting portion, an image of the document is copied onto copy paper obliquely, necessitating another copying operation for the same document.
Further, in the case where the document is set in the document setting portion without passing through the document sensor, the trailing end of the document cannot be detected. Accordingly, the roll paper is cut to a specified size irrespectively of the document size.
In the case where a jam occurs due to the obliquely fed document or copy paper, in the existing image forming apparatus, jam detection is resumed by turning on a reset key after the jammed document or copy paper is removed. Thus, the image forming apparatus is enabled to detect abnormality such as a jam. However, this construction requires a reset key and an operation for turning on the reset key, whereby necessitating a cumbersome operation.